1. Field of the Invention
The present invention relates to an image forming apparatus which receives a print job and performs print processing, a method of controlling the image forming apparatus, and a storage medium storing a program.
2. Description of the Related Art
A print system includes a host computer that generates and transmits a print job to an image forming apparatus, and a print apparatus (image forming apparatus), which prints using the print job received from the host computer. In such a print system, the print job received by the image forming apparatus describes, for example, the arrangement and expression method of texts, images, etc., and the type and size of printing medium used. The image forming apparatus analyzes the received print job to rasterize it into a bitmap image. The rasterized image is printed on the conveyed printing medium using a printing member such as a photosensitive drum or a printing head.
With the recent improvements in image quality and functionality and increase in size of image forming apparatuses, the size of print data designated in a print job is increasing. Hence, an image forming apparatus, which includes a built-in mass storage device typified by a hard disk, has come to be widely used so as to handle large-size data inside the apparatus. In such an image forming apparatus, a hard disk is not only simply used as a buffer memory for print processing but also used as a device for implementing functions having various kinds of added values. In, for example, printing a plurality of copies of print data, after the print data is transmitted from the host computer to the image forming apparatus only once and stored in the hard disk, it is read out from the hard disk by a number of times equal to the number of copies, and is printed. Also, if the printing in progress fails due to, for example, a paper jam, the print data is read out again from the hard disk and printed again.
Moreover, a hard disk is used in another use application. When the type of printing medium set in the image forming apparatus is different from that designated in a print job, the image forming apparatus cannot normally print this job and therefore abnormally stops. When the image forming apparatus has stopped as in this case for a long period of time, it cannot print subsequent print jobs that match the type of printing medium set in this apparatus, either. To avoid this, in such a case, the image forming apparatus suspends print processing for the print job that cannot be normally printed, and temporarily saves it in the hard disk (such a print job will be referred to as a pending job hereinafter), instead of abnormally stopping. The image forming apparatus prints subsequent print jobs ahead of the pending job, thereby being prevented from becoming unavailable because of its abnormal stop (Japanese Patent Laid-Open No. 2002-29123).
Unfortunately, as the number of pending jobs increases, the free space on the hard disk may run short. When this occurs, the image forming apparatus cannot perform print processing even when it receives a new print job from the host computer.